Everyone, not least his Labour colleagues, has had a giggle at the expense of Michael Meacher and his vainglorious bid to become Britain's next Prime Minister. Politics may be unpredictable, but it ain't that unpredictable. The Meachers would be sensible to plan their lives on the basis that they will not be adding Chequers to the family's extensive portfolio of properties. Even the chairman of his campaign launch was not promising to vote for him. Credit, though, where it is due. Michael Meacher may be a fly on a kamikaze mission into the bumper of the Gordon juggernaut, but at least he has the gumption to try to make a contest of it.

Anyone who stands back from the internal machinations and tortured psychology of the Labour party has to regard it as extraordinary that there is still only one member of the cabinet who has declared that he wants to be the next Prime Minister. For the country, what is at stake is the leadership of the United Kingdom. For the Labour party, what is at stake is its capacity so to renew itself that it can win a fourth term.

That is an extremely daunting challenge which requires Labour to 'defy political gravity', in David Miliband's arresting phrase. As things stand, Gordon Brown will become Prime Minister without his party having fully tested whether he is the right man either for them or Britain. That is not to say he doesn't have what it takes; it is to say that it is increasingly astonishing that the Labour party wouldn't want to do some checking.

A paper contest between Gordon Brown and a sacrificial offering from the left-wing Campaign Group will not give an accurate or an attractive representation to the public of the range of Labour opinion. If there's no contest at all, it won't say anything flattering about the quality and courage of the rest of Labour's senior ranks or the party's capacity to have an honest and energising debate about where it wants to take the country.

Every alternative to Gordon Brown has crashed and burned, retired hurt, run away scared or decided to contest for the hollow privilege of being King Gordon's cup-bearer. Hazel Blears yesterday announced herself as the sixth candidate to be the party's number two.

There is no guarantee that the person whom Labour elects as its deputy leader will even become Deputy Prime Minister. Jon Cruddas, the backbencher representing Dagenham who has been running one of the sparkier campaigns, is doing so on the explicit basis that he doesn't want John Prescott's title. It will be entirely within Gordon Brown's power not to have a DPM.

All the contenders for the deputy leadership pay lip-service to the desperate need for Labour to reconnect with the public and rediscover a sense of mission. There is some argument about tactics. Peter Hain suggests a tilt to the left while Hazel Blears contends that Labour must be sure to sustain an appeal to aspirational middle-class voters. But it has so far been an inward-looking affair, a dull debate in the party's navel, a conversation within the dwindled ranks of Labour rather than a contest that engages with and excites the wider public. Not one of the deputy leadership candidates has produced a single sizzling new idea - even a memorable phrase - with the electricity to crackle with the country.

To stand a chance of renewing itself as a government, Labour needs a searching examination about where it has succeeded, where it has failed and what it is going to do in the years AB, After Blair. That is not going to be delivered by an introverted contest for a job that doesn't much matter and a non-existent contest for the job that really does matter.

This might be comprehensible if the Labour party was going to elect Gordon Brown united in the utterly confident knowledge that he has all the answers. But the Labour party is neither united nor confident about that. A hardcore of his detractors have already made up their minds that Gordon Brown will be a poor Prime Minister who will lead Labour to defeat. In the words of one of the former cabinet ministers in this camp: 'We are sleep-walking into a disaster.'

On the other side, and roughly the same size in number, there are the champions of Gordon who predict that the doubters will be eating lashings of humble pie when their hero reveals himself as an awesomely brilliant Prime Minister. They predict that he will pummel callow Cameron into the dust just as soon as he is allowed to get into the ring.

The Gordon zealots and the Anybody But Browns are both minority groups. Much the biggest slice of opinion in the Labour party just doesn't know what to think. His formidable record and talents tell them that the premiership should go to Gordon Brown. Then there's the lack of anyone else with experience that comes anywhere near to competing with that of the Chancellor. Labour MPs are anxious too that a contest would be divisive. It is a sad commentary on the climate of fear in the Labour party that no one can envisage a contest that could be comradely, open and invigorating rather than nasty, closed and destructive.

Respect for Gordon Brown among Labour MPs fights with their anxieties about him. They fret that he lacks Tony Blair's easy ability to communicate with the middle classes. They worry, too, that a man who has been running much of this government for a decade cannot plausibly turn himself into the fresh face of renewal and change. Those misgivings have naturally been heightened by the ICM poll last week for the Guardian. This suggested that Labour would get no surge by switching from Blair to Brown. It would, instead, suffer a further slump. ICM asked how people would vote if Gordon Brown, David Cameron and Sir Menzies Campbell were leading their parties. The result was a 13-point advantage to the Conservatives. That's enough to put David Cameron in Number 10 with a solid majority if there were a general election tomorrow.

There won't be a general election tomorrow, which is one of several reasons to treat that poll and similar ones with some caution. I've spoken to people very high up in the Conservative party who are sceptical of such polls and still expect Gordon Brown to enjoy a bounce with the voters. I've also spoken to extremely senior people at the top of government for whom such polling is a confirmation of their worst fears about Labour's prospects under Gordon Brown. The truth is, no one is sure.

The obvious way for Labour to address the doubts about Gordon Brown would be for him to answer them in a serious leadership contest. David Miliband has articulated the test for Labour which is also the test for its next leader. He wrote: 'We have to get our idealism back, to remotivate ourselves and the country.' The many admirers of the Environment Secretary think the boy David might be better equipped to do that than the Goliath Brown. But writing about it in a newspaper is not the same as actually offering yourself up against a man many years your senior in both age and experience.

The Environment Secretary has been privately pressed to stand by so many people that his arm is now the shape of a corkscrew. In private as well as publicly, he has insisted for months that he won't do it. I detect a slight wobbling in that resolve. Over Christmas, he discussed with those closest to him whether he was right to rule himself out. That is far from saying that he is about to put himself in. One senior Labour figure who is desperate for him to stand puts it like this: 'The first question David has to answer is: do I want it enough?' To challenge Gordon Brown, to take all the risks that would entail, he would really, really have to want it. Even the Environment Secretary's most enthusiastic supporters currently put the chances of him standing at no more than 20 per cent.

I suspect that the polling on Gordon Brown will have to become much more conclusively damning of Labour's chances under him, and much more suggestive that someone else could do better, before a member of the cabinet locates the guts to give him a run for the premiership. The lack of a challenger is the culmination of a decade of planning by Gordon Brown. He has ever been determined that he should be seen as such a preordained leader that no one would dare stand in his way. I've said before that it is a remarkable achievement to sustain the position of heir apparent over so many years. I say it again because it is such an incredible feat.

The trouble is that what suits Gordon Brown does not necessarily suit either the Labour party or the country. I am not even convinced that it is good for him to become Prime Minister without the mandate and the strength that would be conferred on him by a meaningful contest.

It won't be a great start for him to become Prime Minister by default because not one of his cabinet colleagues had the ability or the courage to stand against him. Were I Gordon Brown, I'd want to win with enthusiasm as the right man for the job, not get there merely because I was regarded as crushingly inevitable.

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